1. Field Of the Invention
The present invention relates to an image forming apparatus and image forming method for forming an image on a recording medium by developing an electrostatic latent image, and specifically relates to an image forming apparatus and image forming method for image formation using ink.
2. Description of the Related Art
Conventional image forming apparatuses of the so-called electrophotographic type have become widely popular as electrophotographic copiers. The electrophotographic process is an image forming method comprising a process for uniformly charging the surface of a photosensitive member to a given polarity, a process for optically exposing said charged photosensitive member, a process for developing the formed electrostatic latent image using a developer containing a toner having a predetermined charge so as to obtain a visible image (toner image), a process for transferring said toner image from the photosensitive member to a recording sheet, and a process to fuse said toner image on said recording sheet. The electrophotographic process executes continuous image forming processes starting from the aforesaid process for charging the photosensitive member, and executes a cleaning process to remove residual toner from the surface of the photosensitive member, and an erasure process to eliminate residual charge from the photosensitive member between each consecutive image forming process. Dry type developer which develops a latent image using dry toner particles, and wet type (liquid) developer which develops a latent image using toner particles dispersed in a carrier fluid are used as developers in the electrophotographic process.
Although the electrophotographic process is an image forming method which has advantages such as excellent image quality, it does include certain disadvantages arising from developing an electrostatic latent image using toner particles having a predetermined charge inasmuch as, for example, dispersion in the amount of charge held by the toner particles causes toner particles to adhere to non-image areas of the photosensitive member, i.e., areas on which an electrostatic latent image is not formed, which results in image noise referred to as fog in the non-image areas of the image formed on a recording sheet. A further disadvantage of the electrophotographic process is the complexity between the apparatus construction and the executed processes which arises from the relationship between the photosensitive member and the toner used.
On the other hand, there are well known image forming methods which simplify the apparatus construction and processes, for example, by forming an electrostatic latent image on a dielectric element via discharge of a thin wire electrode or the like, developing said electrostatic latent image using ink, and transferring the obtained ink image to a recording sheet to produce an image. In this type of image forming process, however, a disadvantage arises inasmuch as there is a strong adhesion force between the ink and the dielectric element such that inadequate transfer to the recording sheet readily occurs. A further disadvantage to this type image forming method is that ink readily adheres to the non-image areas during development so as to produce fog in the image even after transfer to the recording sheet.